The Warning Under the Houses

The underside of the fragment was coming apart beneath Mercy’s wheels. Houses hung from it in crooked rows, their foundations exposed to open sky, and the red signal flashed from somewhere among them. Each pulse showed Oliver another stretch of the collapsing route.

“Keep the white line clear of it,” Nadia said. Her palm rested against the brass panel, gold light threading beneath her skin. “The red signal has its own way through.”

Oliver watched the gauge. Two narrow marks ran beside the exhausted blank reserve: Sera’s white route, steady alongside the engine, and the red one, flickering beneath the houses. “I can follow it. I can’t tell where it ends.”

“Then we find out without making it ours.”

The rail pitched down. Oliver eased Mercy along it, keeping the engine’s speed low while the fragment turned around them. A row of chimneys passed overhead. Loose bricks fell toward the sky, then halted against separate points of gold as Nadia caught the shifting masonry. She kept each support apart. The engine stayed level while the stone around it rotated.

Ahead, the rail stopped at a broken bridge. Its remaining span hung in two pieces, the gap between them widening as the fragment twisted. Oliver braked. The white lantern beside Sera’s seat continued to glow.

The Horologist stood on the far side of the gap, one hand resting on a brass watch chain. He wore the same plain dark coat Oliver remembered from the other broken crossings. No train waited behind him.

“Mercy’s line ends here,” Oliver called.

“For this crossing,” said the Horologist. “The undertrain keeps its own schedule.”

“Is it on the other side?”

“It is where its passengers have chosen to go.” He glanced toward the red signal below the bridge. “A road can meet another road without becoming its track.”

Nadia held her hand out. Gold points lit along the two pieces of bridge, one by one. They did not fuse into a single span. Oliver drove across each supported section as it settled beneath the wheels. The gap narrowed enough to pass, then opened behind the engine.

The Horologist was gone when Oliver looked back. Mercy’s rail continued down, separate from the darkness beneath the fragment.

The red flashes now came through the windows of a house hanging below the track. Oliver brought the engine to a stop beside its roof. A stairwell had split the building from top to bottom; its lower flight dangled loose, turning slowly. Red light pulsed at the landing below.

Sera lifted her lantern. “That’s a warning pattern.”

“You know it?” Oliver asked.